Predictive transformation

[bnadim]

i tried to used dedent and came accros two issues :
First i had some bug with \` being transformed the wrong way (i can't remember exactly)
Second is if you try for example to add a first blank line or you want to tab all you text you can't.

Here is the short module i ended up writing to overcome both. If you want i could make it a pr.
Code here : https://github.com/ekino/veggies/blob/master/src/extensions/snapshot/dedent.js
tests here : https://github.com/ekino/veggies/blob/master/tests/extensions/snapshot/dedent.test.js

For commodity here is the code

/**
 * Extract spaces length
 * @param {string} text
 * @returns {number} length tab and space before first char
 */
const getSpacesLength = text => {
    let length = 0

    while (length < text.length) {
        const char = text[length]
        if (char !== ' ' && char !== '\t') break
        length += 1
    }

    return length
}

/**
 * Used to remove indentation from a text. Usefull with multine string in backticks.
 *
 * Two way to use it : `
 *     My text
 *       Another line
 *     Another line again
 * `
 * the result text will be :
 * "My text
 *   Another line
 * Another line again"
 *
 * In this case, alignment is done on the length of the first character that is not a space or a tab of all lines
 *
 * Or
 *
 * Another way : `
 *     """
 *       My text
 *         Another line
 *      Another line again
 *     """
 * `
 * the result text will be :
 * "  My text
 *      Another line
 *  Another line again"
 *
 *  In this case, alignment is donne on the spaces or tab before """
 *
 * Warning : First line and last line will always be ignored
 *
 * @param {string} text
 * @return {string}
 */
module.exports = text => {
    if (typeof text !== 'string') text = text[0]

    let lines = text.split('\n')
    if (lines.length < 3) return text

    lines = lines.slice(1, lines.length - 1)

    let skipLength = getSpacesLength(lines[0])

    if (
        lines[0].substr(skipLength, 3) === '"""' &&
        lines[lines.length - 1].substr(skipLength, 3) === '"""'
    ) {
        lines = lines.slice(1, lines.length - 1)
    } else {
        for (let i = 0; i < lines.length; i++) {
            const line = lines[i]
            skipLength = Math.min(skipLength, getSpacesLength(line))
        }
    }

    const resultLines = []
    for (let i = 0; i < lines.length; i++) {
        resultLines.push(lines[i].substring(skipLength))
    }

    return resultLines.join('\n')
}